Method of preparing adducts



Patented Dec. 1, 1953 METHOD OF PREPARING ADDUCTS Joachim Dazzi, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application February 15, 1950, Serial No. 144,393

3 Claims. (Cl. 260404.8)

This invention relates to improvements in the preparation of adducts formed by the addition reaction of maleic anhydride with olefinic, nonconjugated, unsubstituted fatty acids of from to 24 carbon atoms, and esters of said acids. It has particular reference to improving the color and clarity of such adducts.

ihe preparation of adducts by reaction of maleic anhydride with unsaturated fatty acids is well-known. (See U. S. Patent No. 2,138,882 to Clocker and the article by Ross, Gebhart and Gerecht, which appears in the Journal of the American Chemical Society, p. 1373 (1946).) While the structure of such adducts has not been definitely determined, it is believed that addition of the fatty acid or ester thereof, occurs at the double bond of the dicarboxylic acid. For example, the maleic anhydride-oleic acid adduct probably has the structure:

Owing to uncertainty of the position of the fatty acid carbon at which attachment of the dicarboxylic residue occurs, as well as for the sake of brevity, the term adducts employed hereinafter Will refer to the equimolar addition products of maleic anhydride and a fatty acid compound having the general formula:

YCOOZ wherein Y is an olefinic, aliphatic, hydrocarbon residue of from 9 to 23 carbon atoms and Z is an alkyl group of from 1 to 8 carbon atoms, and hydrogen.

Such adducts, as pointed out in the Clocker patent referred to above as well as in my copending patent applications, Serial Nos. 144,391 and 144,392, filed February 15, 1950 and issued as U. S. Patent Numbers 2,569,404-5, respectively, both dated Septembr 25, 1951, are compounds of great potential use in the chemical and related industries. Actual utilization of the adducts, however, has been somewhat limited by their poor color. For example, when following the procedure employed in the Clocker patent there are generally obtained, even when using very pure grades of reactants, opaque reaction materials of a dark color that makes them unsuitable for many uses for which they could be otherwise employed.

Accordingly, an object of the present invention is to provide a method for improving the color of such adducts.

Another object of the invention is to provide a method for preventing, or at least minimizing decolorization of the product in the addition reaction of maleic anhydride and olefinic, nonconjugated, unsubstituted fatty acids of from 10 to 24 carbon atoms or esters of such acids.

These and other objects of the invention may be accomplished by the process of the invention which comprises using with the maleic anhydride and the fatty acid compound a small amount of an inorganic oxyacid of phosphorus or an ester thereof. While I do not know the mechanism of the color-inhibiting efiect of such phosphorus compounds when employed in the reaction mixture it may be assumed that they either react with some impurity or impurities that may be present in the reactants or that they retard side reactions which contribute to the darkening of the desired adducts. Inasmuch as the addition reaction readily takes place in the absence of the phosphorus compounds, the action of the added material cannot be considered to be catalytic. Only very small quantities of the phosphorus compound need to be employed, say, from 0.5 per cent by weight to 5 per cent by weight of the maleic anhydride employed. Less than 0.3 per cent generally has substantially no decolorizing efi'ect and while quantities in excess of 5 per cent may be employed, for purposes of economy it is preferred to limit the range of the additive to not more than 5 per cent, this quantity being sumcient to give adducts of greatly improved color.

Phosphorus compounds employed in the present invention comprise the various acids, e. g., orthophosphoric acid, metaphosphoric acid, pyro phosphoric acid, hypophosphoric acid, orthophosphorous acid, hypophosphorous acid and pyrophosphorous acid. Partial or total esters of acids may be used instead of the free acids, i. e., esters of said phosphorus acids with aliphatic, alicyclic, aralkyl, or heterocyclic hydroxy compounds, e. g., tri-n-butyl phosphate, tri-phenyl phosphate, dibenzyl pyrophosphate, mono-cyclohexyl hypophosphate, tri-furyl phosphate, etc. Particularly useful are the alkyl and aryl esters in general and the following aliphatic and aromatic esters: triand are based on the determination of unreacted ethyl phosphite, di(fi-chloroethyl) phosphite, maleic anhydride found in the filtrate and in the tris(fi-butoxyethyl) phosphite, 2 ethylhexyl solid residue. This method was also checked by metaphosphate, lauryl phosphate, tri-o-cresyl polarographic determination of maleic anhydride phosphite, fi-naphthyl phosphite, tri-p-anisyl found in the filtrate before and after the water phosphite, and tri(4-nitrophenyl) phosphite. Wash.

Table I Experiment No l 2 3 4 5 13 Eme1s01-233 13.8 13.8 13.8 282.5

Ahcolein-810 13.8 13.8 10-Undceylcnic Acid... 368.5 Maleic Anhydride s. 0 o. 0 c. 0 0.0 e. 0 246 122. 5 Triphenyl Pliosphite 2 (percent) 1.0 1.0 2.0 2.0 0.0 2 0 2.0 Hole Ratio: Maleic Anliydridez Fatty Acid 1. 1. 25 1 25 1.25 1.25 1 25 1 25 Heating Time 3 (Hrs) 4 4 4 4 4 4 6 Temperature, C"... 209 209 209 200 209 218 200 Color 4 13 o 12.0 14 2 12.0 16.0 13. 7 12.0

1 Emersol-233 (Emery Ind.) and Ahcolein-BIO (Arnold, Hoffman) represent distilled oleic acid, technical.

2 Based on charged maleic anhydride.

3 After reaction mixture had been brought to 200 C.

4 Gardner Scale (Gardner Color Standards for Varnishes, Oils and Lacquers).

The invention is further illustrated, but not Quantities of reactants indicated above are limited by the following examples: parts by weight. Experiments 1 to 5 were carried 25 out in large size test tubes, fitted with a cork EXAMPLE 1 stopper wrapped in metal foil, and Experiment 13 was carried out in a three-necked flask, equipped In s example there is Summarlzed a Serles with stirrer, condenser and thermometer. Ex- Of eXperimentS Which Were made according to the periments 1 to 5 Were heated simultaneously in following genera1 p the same oil bath. In Experiments 13 and 15 the Into a three-necked fiaslc fitted with an agiunreacted maleic anhydride Was removed by tator, thermometer, condenser and an inlet tube Washing with Water bef measuring the color there were placed the fatty unsaturated acid, the of the product. maleic anhydride and th phosphorus Compound- The improvement in color which was obtained. The molar ratio of maleic anhydridezoleic acid by operating in the presence of the phosphorus used Varied between The Off gases 01' ompound is remarkable Thus as hown in the traces of maleic anhyd Were Collected Over above table, in the blank Experiment 5, the very ted aqueous Sodium hydroxide and a color or" the adducts on the Gardner scale was few drops of p nolphthalein. 16.6. The efficiency of the introduced phos- The Whole mixture was heated during a 30 40 phorus compound is shown by the decreased color mi ute period from room p e p 110 value of the adducts prepared in the presence C. (liquid temperature). An inert gas,i.e.,nitroof t indicated phosphmus acid or ester, W s bubbled ug t e liquid during the asmuch as each unit in the upper range of the first 15 minutes of the half-hour heating P Gardner scale, i. e., in color values of from 10 After a 4 to 6' hour heating period at the temperat 15 represents a decidedly significant color tures indicated in the table below, the mixture change t results t i by t present proc was cooled t0 approximately -r then treated ess are of great industrial importance, particuwith clay and a filter aid, and stirred for 30 min- 1 1 i th plastics field utes. The reaction mixture was subsequently treated with charcoal and stirring was continued EXAMPLE 2 for an additional 30 minutes at to C. This example is like Example 1, except that The product was then filtered over a filter aid. instead of employing triphenyl phosphite as the The filtrate was diluted with ether, washed sevphosphorus compound, the esters indicated in the oral times with water and the wash Water anatable below were used.

Table II Experiment N0 5 7 8 9 12 Poommund Used Tri-n-butylphosphite. Tri-n-butylph0sphite 2 ty1 hyp -phos- Tri-n-butylphosphit Emersol-233 1 Ahcolein-BIO 10-Undceylenic Acid Maleic Anhydride Percent P Compound Used Mole Ratio: Malcic Anhydridez'l atty Acid.

Heating Time 3 (Hrs). Temperature, 0. Color 4 1 Emcrsol-233 (Emery Ind.) and Aheelein-SIO (Arnold, Hoffman) represent distilled oleic acid, technie 1 2 Based on charged maleic anhydride.

3 After reaction mixture had been brought to 200 C.

4 Gardner Scale (Gardner Color Standards for Varnisbes, 011s and Lacquers).

H ms

menace p lyzed maleic anhydride- LOW boiling ma- Quantities of reactants indicated above are terials were removed by heating the residue for 1 parts by weight. All of the above experiments to 2 hours at 100 C. bath temperature at 1 mm. were carried out in large size test tubes, fitted Hg. The yields varied between 86 to 96 per cent with a cork stopper wrapped in metal foil, and

all were heated simultaneously in the same oil bath.

Example 3 This example is like Example 1, except that instead of employing triphenyl phosphite as the phosphorus compound, the phosphorus acids indicated in the table below were used.

Table III Experiment No 5 l0 ll 14 1? Compound Used Phosphorous Acid... Phosphoric Acid H y o p 1 0 S p h 0 r 0 u 5 Acid. Emersol-233 1 212. Ahcolein-8l0 1 IO-Undecylem'c Acid Maleic Anhydride Temperature, C Color 4 1 Emersol-233 (Emery Ind.) and Ahcolein-BIO (Arnold, Hofiman) represent distilled oleic acid, technical.

2 Based on charged maleic anhydride. 3 After reaction mixture had been brought to 200 0.

4 Gardner Scale (Gardner Color Standards for varnishes, Oils and Lacquers).

Quantities of reactants indicated above are parts by weight. Experiments 5, 10 and 11 were carried out in large size test tubes, fitted with a cork stopper wrappedin metal foil. Experiment 14 was conducted in a three-necked flask, equipped with stirrer, condenser and thermometer. Experiments 5, 10 and 11 were heated simultaneously in the same oil bath. In Experiment 14 the unreacted maleic anhydride was removed by washing with water before measuring the color of the product.

Although the above examples show only the use of oleic acid and undecylenic acids as the fatty acid components, other olefinic, non-conjugated, unsubstituted fatty acids may be similarly reacted with maleic anhydride in the presence of the present phosphorus compounds to give adducts of good color. Also, instead of using the free fatty acids, there may be employed esters of the same with aliphatic, unsubstituted alcohols of from 1 to 8 carbon atoms, e. g., methyl, ethyl, isopropyl, n-hexyl or Z-ethylhexyl undecylenate or oleate, the adducts thus obtained being clearer and lighter in color than adducts prepared by prior methods.

While I prefer to add the phosphorus compound to the mixture of maleic anhydride and the fatty acid component before initiating the reaction, good results are also obtained when the present phosphorus compounds are added at an intermediate stage of the reaction. For example, the reaction mixture may be heated for a time of, say, one to two hours in the absence of the phosphorus compound, and the reaction interrupted for addition of the latter. However, color improvement is not so pronounced.

Inasmuch as formation of the present adducts involves addition of one mole of the maleic anhydride with one mole of the fatty acid compound, these reactants should be present in substantially stoichiometric proportions. However,

While the addition of maleic anhydride with the fatty acids occurs readily at ordinary atmospheric pressures, with some reactants use of lower or greater pressures is advantageous. The addition reaction may also be efiected in the presence of an inert diluent, the use of a diluent being recommended when working with the higher esters, e. g., n-octyl oleate.

What I claim is:

1. The process of preparing adducts which comprises heating, at temperatures of from 150 C. to 300 0., a mixture comprising maleic anhydride, oleic acid and an aryl ester of an acid selected from the class consisting of phosphorous acid and hypophosphorous acid, the quantity of said aryl ester being from 0.5 per cent to 5.0 per cent by weight of the weight of the maleic anhydride.

2. The process of preparing adducts which comprises heating, at temperatures of from 150 C. to 300 C., a mixture comprising maleic anhydride, oleic acid and triphenyl phosphite, the quantity of said phosphite being from 0.5 per cent to 5.0 per cent by weight of the weight of the maleic anhydride.

3. The process of preparing adducts which comprises heating, at temperatures of from 150 C. to 300 C., a mixture comprising maleic anhydride, 10-undecylenic acid, and triphenyl phosphite, the quantity of said phosphite being from 0.5 per cent to 5.0 per cent by weight of the weight of the maleic anhydride.

J OACHIM DAZZI.

Number Name Date Rust Dec. 22, 1942 

1. THE PROCESS OF PREPARING ADDUCTS WHICH COMPRISES HEATING, AT TEMPERATURES OF FROM 150* C. TO 3000* C., A MIXTURE COMPRISING MALEIC ANHYDRIDE, OLEIC ACID AND AN ARYL ESTER OF AN ACID SELECTED FROM THE CLASS CONSISTING OF PHOSPHOROUS ACID AND HYPOPHOSPHOROUS ACID, THE QUANTITY OF SAID ARYL ESTER BEING FROM 0.5 PER CENT TO 5.0 PER CENT BY WEIGHT OF THE WEIGHT OF THE MALEIC ANHYDRIDE. 